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Biomedical subjects

N Samman

Publications and source records attributed to N Samman.

At least 19 recordsLinked to original sources
PubMed2000

Computer-assisted three-dimensional surgical planning and simulation: 3D color facial model generation.

A scheme for texture mapping a 3D individualized color photo-realistic facial model from real color portraits and CT data is described. First, 3D CT images including both soft and hard tissues should be reconstructed from sequential CT slices, using a surface rendering technique. Facial features are extracted from 3D soft tissue. A generic mesh is individualized by correspondence matching and interpolation from those feature vertices. Three digitized color portraits with the "third" dimension from reconstructed soft tissue are blended and texture-mapped onto the 3D head model (mesh). A color simulated human head generated from frontal, right and left real color portraits can be viewed from an arbitrary angle in an inexpensive and user-friendly conventional personal computer. This scheme is the basic procedure in 3D computer-assisted simulation surgery.

Color↗
PubMed2000

Computer-assisted three-dimensional surgical planning and simulation: 3D virtual osteotomy.

A computer-assisted three-dimensional virtual osteotomy system for orthognathic surgery (CAVOS) is presented. The virtual reality workbench is used for surgical planning. The surgeon immerses in a virtual reality environment with stereo eyewear, holds a virtual "scalpel" (3D Mouse) and operates on a "real" patient (3D visualization) to obtain pre-surgical prediction (3D bony segment movements). Virtual surgery on a computer-generated 3D head model is simulated and can be visualized from any arbitrary viewing point in a personal computer system.

Algorithms↗
PubMed2000

Computer-assisted three-dimensional surgical planing and simulation. 3D soft tissue planning and prediction.

The purpose of this paper is to report a new technique for three-dimensional facial soft-tissue-change prediction after simulated orthognathic surgical planning. A scheme for soft tissue deformation, "Computer-assisted three-dimensional virtual reality soft tissue planning and prediction for orthognathic surgery (CASP)", is presented. The surgical planning was based on three-dimensional reconstructed CT visualization. Soft tissue changes were predicted by two newly devised algorithms: Surface Normal-based Model Deformation Algorithm and Ray Projection-based Model Deformation Algorithm. A three-dimensional color facial texture-mapping technique was also used for generating the color photo-realistic facial model. As a final result, a predicted and simulated patient's color facial model can be visualized from arbitrary viewing points.

Algorithms↗
PubMed1999

Custom-made titanium mandibular reconstruction tray.

Reconstruction of the mandible after ablative surgery can be achieved by using preformed trays or trays formed from models produced by computer-assisted modelling systems. The former presents difficulty in matching the required facial contour, jaw relationship and condylar position; while the latter is expensive. This paper presents a simple and inexpensive method of fabricating a custom-made titanium bone grafting tray. The dimensions of the patient's mandible are obtained by clinical measurement. Such measurements are used to construct a mandibular replica. The region to be reconstructed is carved to produce the ideal shape and dimensions of an edentulous segment. The tray is made either by casting or by swaging. Twenty-one custom-made titanium bone grafting trays have been fitted in patients with encouraging results. This method of bone grafting tray construction is a simple, inexpensive technique for achieving excellent facial contour and functional reconstruction after mandibulectomy.

Bone Transplantation↗
PubMed1999

[Investigation needs on carotenoids in the republic of Argentina].

There are no national dietary surveys regarding nutrient intake of Argentine population. On the other hand, nutrient content of foods in Argentina, as in other Latin American countries, is unknown because there are no data on food composition. Therefore, nutrient intakes must be calculated using foreign composition tables. In relation to vitamin A nutritional status, high prevalence of low vitamin A intake and low plasma retinol levels have been found in the eighties in several groups of university students. In this report, results of a 7-day dietary survey of students attending the course of Nutrition in the Universities of Buenos Aires, Luján and Tucumán are presented. Information was processed in a PC Computer (VAN Program, Lujan University, Argentina) to obtain the mean daily intake of carotenes with and without provitamin A activity, according to the German Food Composition Tables. The results showed that provitamin A carotenes provided between 40 and 82% of the vitamin A recommended allowances and that about 20% of the population had total carotene intake lower than 4 mg/day. These results are in agreement with other dietary surveys carried out in students in previous years and are a consequence of some characteristic feeding habits of the Argentine population. In order to obtain more reasonable results regarding actual intakes in our population, study of the composition of national foods would be imperative.

Antioxidants↗
PubMed1998

Cephalometric characteristics of anterior open bite in a southern Chinese population.

The cephalometric characteristics of skeletal anterior open bite (AOB) in a southern Chinese population were evaluated in a group of 104 subjects with AOB and were compared with a control group of 40 subjects without AOB. The anteroposterior jaw relationship in the AOB group was Class I in 43%, Class II in 14%, and Class III in 43%. Cephalometric analysis of all subjects was completed by using 24 skeletal and 12 dentoalveolar measurements. Sexually dimorphic variables were identified and compared separately between groups with independent t tests. Two levels of significance were used, P < or = 0.05 and P < or = 0.001. Sexual dimorphism of cephalometric variables was present in both the test and the control groups, but affected more variables in the test group. Significant findings in AOB were shorter anterior cranial base, upward and forward rotation of the maxilla, increased gonial and mandibular plane angles, increased upper posterior dental height, and increased lower anterior facial height. These findings generally coincided with those for white subjects, however, there was no conclusive evidence in this study regarding the contribution of the upper anterior facial height or the posterior facial height to the AOB deformity.

Adolescent↗
PubMed1998

Functional reconstruction of the mandible: a modified titanium mesh system.

This paper describes a method for mandibular reconstruction utilizing autogenous cancellous bone in a titanium mesh. The mesh is designed preoperatively based on a duplicate of the patient's mandible which is modified to simulate an anatomically correct edentulous segment in the region to be reconstructed. The duplicate mandible is articulated with a maxillary dental cast, and a locating splint is fabricated for intraoperative use to aid the positioning of the mesh in relation to the upper teeth. The method facilitates future rehabilitation with dental implants and results in a symmetric and highly functional reconstruction of the mandible.

Adult↗
PubMed1998

Posterior maxillary anatomy: implications for Le Fort I osteotomy.

The most common site of haemorrhage in maxillary osteotomies is the posterior maxilla. Better understanding of the anatomy in this region may minimize possible vascular complications. The aim of the study was to study the osteology of the posterior maxillary region and establish clinical safety guidelines for the Le Fort I osteotomy Thirty human dry skulls were selected and assessed by a combination of direct inspection, computerized imaging and computed tomography (CT) scan analysis. Results showed that the presence of maxillary third molars influenced the transverse angulation of the posterior vertical cut. Synostosis of the pterygomaxillary junction was noted in 12% of samples. The mean length of the medial sinus wall from the piriform rim to the descending palatine canal at the Le Fort I level was 34 mm. The three-dimensional CT-reconstructed descending palatine canal ran at 60 degrees anteroinferiorly to the palatine plane and slightly medially to the exit through the greater palatine foramen.

Adult↗
PubMed1998

A modified approach to the Le Fort II osteotomy.

A modified technique of Le Fort II osteotomy is described for the correction of naso-maxillary hypoplasia. The surgical access was via a combination of bicoronal flap and transoral sulcular incision. Any periorbital skin incision is avoided. This is made possible by having the medial orbital cut made through the lacrimal groove. The anterior limb of the medial canthal ligament is detached, but leaving the posterior and superior limbs intact. Following mobilization, the osteotomy segment is stabilized by miniplates without intermaxillary fixation. This method eliminates the need for facial incision and hence the residual scar. Patients' recovery and acceptability of this modified approach to Le Fort II osteotomy is much enhanced.

Humans↗
PubMed1997

A bone graft condensing syringe system for maxillofacial reconstructive surgery.

A new system of metallic syringes and pluggers specifically designed for delivery and condensation of particulate bone graft is reported, and the clinical application in maxillofacial reconstructive surgery is described. This bone graft condensing system has advantages over the conventional plastic injection syringes in enabling much better bone graft condensation as well as easier bone delivery and insertion of the syringe to the depth of the reconstruction crib.

Bone Transplantation↗
PubMed1997

Temporalis myofascial flap in maxillofacial reconstruction: clinical and histological studies of the oral healing process.

OBJECTIVES: To report our experience with temporalis myofascial flaps (TMF), describe the healing process of uncovered flaps in the mouth, and the histology of the repaired mucosa in the long term. DESIGN: Prospective clinical and histological study. SUBJECTS: 36 patients who received a TMF over a 6.5 year period for serial assessment of the oral healing, 24 patients whose scars over the reconstructed area were assessed clinically, and 11 whose repaired mucosa was assessed histologically. MAIN OUTCOME MEASURES: To follow the clinical process of oral healing of the TMF and describe the repaired mucosa healed over the flap. RESULTS: The uncovered TMF in the mouth healed gradually starting with an acute inflammatory phase, going through chronic inflammatory and proliferative phases with eventual epithelialisation of the oral mucosa. There were no major complications. The healed mucosa showed mild scarring in 70% of cases and the repaired mucosa had characteristic histological features that were distinct from the normal mucosa. CONCLUSION: The TMF is an extremely reliable and versatile flap for maxillofacial reconstruction which heals gradually with eventual coverage by mildly scarred repaired mucosa.

Adolescent↗
PubMed1997

Cephalometric parameters affecting severity of anterior open bite.

One hundred and four patients with anterior open bite (AOB) were subdivided by statistical means into three distinctly separate groups with AOB of different severity based on the extent of separation of the incisors in the vertical plane. Cephalometric evaluation of all subjects was completed using 24 skeletal and 12 dentoalveolar measurements, and the results were compared between the mild, moderate and severe groups of AOB. The findings suggest that the palatal plane, mandibular occlusal plane, upper anterior dental height and upper posterior dental height correlate significantly with the severity of AOB. In contrast, skeletal jaw relationship in the horizontal plane correlated only weakly with severity. This study further highlighted the steep mandibular occlusal plane as an important indicator of AOB severity in contrast to the maxillary occlusal plane.

Adolescent↗
PubMed1997

[The healing process of the temporalis myofascial flap in oral reconstruction].

From a prospective study of 36 patients having had temporalis myofascial flap (mean follow-up 32 months), the clinical oral healing process and the histological characteristics of the repaired mucosa were investigated. Among this group, 24 patients were assessed of the clinical scarring over the reconstructed area and 11 patients for histological evaluation of the repaired mucosa. Result showed that the uncovered temporalis myofascial flap in the mouth underwent a consistent healing commencing with an acute inflammatory phase, through chronic inflammatory and proliferative phases to eventual epithelialization by oral mucosa. No major complications affecting the healing flap were noted. The healed mucosa exhibited scarring in 70% of cases and the repaired mucosa demonstrated histological features distinct from the normal mucosa.

Adolescent↗
PubMed1996

Blood loss and transfusion requirements in orthognatic surgery.

PURPOSE: This study quantified the blood loss and transfusion requirements in orthognathic surgery. PATIENTS AND METHODS: Three hundred sixty consecutive healthy orthognathic surgery patients were included in this retrospective study. The female:male ratio was 1.8:1, and the age range was 8 to 49 years (mean, 24). Estimated blood volume (EBV), estimated blood loss (EBL), and transfused blood were calculated. RESULTS: EBL ranged from 50 to 5,000 mL (mean, 600) representing up to 73% of EBV (mean, 16%). In total, 24% (84 patients) were transfused, 8.7% (6 patients) after single-jaw surgery and iliac bone harvest and 26.7% (78 patients) after bimaxillary osteotomies. Forty-seven patients received 1 unit of transfused blood, 25 patients had 2 units, and 12 patients had more than 2 units. Most transfused patients lost 11% to 40% of EBV. CONCLUSIONS: Transfusion is not necessary for single-jaw surgery unless a bicoronal flap or iliac bone harvest are required. Although only 27% of bimaxillary osteotomy patients required transfusion of 1 to 2 units, this group was not predictable based on the type of procedure involved, and a further subgroup (4% of the 291 patients) required a larger transfusion.

Adolescent↗
PubMed1996

Ultrastructural identification of cells involved in the healing of intramembranous and endochondral bones.

This study was designed to identify the cells involved in the healing of autogenous intramembranous (IM) and of endochondral (EC) bone grafts. Thirty-six defects were created in the skull of 18 adult New Zealand White rabbits. Defects were filled with IM graft alone, EC graft alone, demineralized bone matrix (DBM) alone, or combined DBM-IM and DBM-EC bone. Cellular identification was carried out at 7 and 14 days by light and electron microscopy. In IM bone, preosteoblasts, osteoblasts, and osteocytes were observed with no cartilage intermediate stage, while in EC bone, chondroblasts and chondrocytes were observed. DBM implant and DBM-IM were characterized by the presence of a cartilage stage. In conclusion, IM bone healed through an osteogenic ossification route, while EC bone healed through an EC ossification route. In the presence of demineralized EC bone matrix, IM bone adopts an EC ossification route.

Animals↗
PubMed1996

An unusual facial sinus.

An unusual presentation of a chronic suppurative granuloma on the alar base area originating from a maxillary lateral incisor is reported. Treatment involved adequate endodontic therapy with simultaneous apical surgery and excision of the granuloma and sinus tract. Awareness of the possible dental origin of facial sinuses, despite their unusual location, is emphasized.

Adult↗
PubMed1996

Inflammatory pseudotumour of the mouth and maxilla.

AIM: To describe the clinicopathological and immunophenotypical findings of two cases of inflammatory pseudotumour in the oral cavity. METHODS AND RESULTS: The patients presented with a short history of swelling in the cheek and the maxilla respectively. Magnetic resonance imaging or computerised tomography scan showed space occupying lesions with infiltrative margins which were interpreted as aggressive malignant neoplasms. Histological examination showed fascicles of spindle cells in a background of chronic reactive inflammatory cells including plasma cells, typical of inflammatory pseudotumour. The spindle cells were positive for vimentin, smooth muscle actin and CD68, but were negative for follicular dendritic cell markers. The lymphocytes showed no light chain restriction. CONCLUSIONS: Inflammatory pseudotumour in the oral cavity is completely benign and simple excision is curative. However, it may be confused with a malignant tumour on clinical and radiographic grounds, and histologically the appearances can also be misinterpreted as those of a more aggressive lesion. Its correct recognition by the surgical pathologist is important to avoid unnecessarily radical and potentially mutilating surgery.

Adult↗